Restriction(s)

Identifier non-conformity

This restriction is associated with data collections whose published identifier scheme does not follow the recommended requirements. For example, such identifiers may contain too much semantic information which could hinder their future stability (such as been composed of words or partial sentences). Users should consult the specific documentation given by the data provider.

The reason why this restriction is associated with the parent data collection is: Identifiers are the structural representation of a substance.

Identifier independence

This restriction is associated with identifiers that are not associated with an individual data collection. These collection-independent identifiers may potentially be used to both identify an entity, as well as provide some further information. Examples include InChi and InChiKey, which provide structural information for chemical entities.

The reason why this restriction is associated with the parent data collection is: Identifiers are not restricted to a specific data collection.